The new version of the system powers the electric motor-generator from a small lithium-ion battery pack, mounted at the base of the trunk toward the rear seat.

For better gas mileage, the eAssist version of the Lacrosse also comes with active grille shutters to lower its aerodynamic drag at speed.

In practice, this means that the engine in the Lacrosse with eAssist switches off when the car is stopped, then restarts as soon as the driver's foot starts to lift off the brake pedal.

Restarting, adding power

That's the only benefit Buick chose to show in its introductory ad for the Lacrosse with eAssist, but there's another benefit to the system's more powerful 15-kilowatt (20-hp) electric motor as well.

The motor not only starts the engine, but also contributes added electric torque to the engine when a little more power is needed. In practice, this means the car's six-speed automatic transmission needs to upshift less.

That allows the 182-horsepower, 2.4-liter engine to continue running at lower, more economical speeds--not to mention making the Lacrosse slightly smoother and quieter in use.

36 mpg highway

The net result is much better fuel economy. The EPA rates the four-cylinder 2012 Lacrosse at 25 mpg city, 36 mpg highway, for a combined gas mileage figure of 29 mpg.

That's remarkable for such a large near-luxury sedan, and it's far better than the 19 city, 30 highway, and 23 combined of the 2011 model using the same engine, but without the eAssist system.

Though hybrid near-luxury sedans are hardly their own category, likely competition for the 2012 Lacrosse hybrid includes the slow-selling Lexus HS 250h (35 mpg combined) and the Lincoln MKZ Hybrid (39 mpg combined).

Buick also suggests the Acura TL (23 mpg combined), though we think that car's performance leanings and urban and high-tech audience isn't particularly a match for probably Lacrosse buyers.

So as not to scare those buyers, Buick refers to the Lacrosse eAssist system as "light electrification," and it tends to avoid the dreaded H-word in its marketing for the car. Wouldn't want anyone to think it was a Prius, now, would we?

A large sedan

To be honest, the 2012 Buick Lacrosse--with or without eAssist--is not a vehicle we particularly relish driving. It's a surprisingly large sedan, weighing almost 2 tons and stretching 16 and a half feet long.

And the proportions of the cabin from behind the wheel felt a little oversized for our six-foot driver, with the armrests on the door and console just a bit too far apart. In other words, this seems to be a car for large Americans.

The window openings are short, the beltline rises toward the rear, and occupants sit low in the car, meaning outward visibility isn't great. Five-foot tall rear-seat occupants may not even be able to see out their windows.

From the inside out, in fact, the base of the windshield pillars creates a blind spot that's so large we almost missed an approaching bicyclist. The thick pillars are second only to those of the Chevy Volt in blocking outward vision, and we'd like to have a stiff word with GM's safety engineers about them.

This the the most stylish and affordable American luxury car, IMHO, and now it's even better with the eAssist feature. Credit should go to GM for their attempts to be green in the luxury market.

John
Posted: 12/7/2011 4:17am PST

It will be interesting to see how many consumers opt for the 29 mpg hybrid versus the 21 mpg V6.

John
Posted: 12/7/2011 4:47am PST

Wonder why you would ever use the electric e-brake. Perhaps parking on a hill.

John
Posted: 12/8/2011 5:00am PST

I figured it out. Voelcker was frustrated by the noise of the electric e-brake during all his handbrake turns :)

John
Posted: 12/11/2011 4:14am PST

@John: Not quite sure I'm understanding this comment. It's a good idea always to use the emergency brake when parking, especially on any kind of slope. It takes the pressure off the locking pin in the automatic transmission, and provides a second method (redundant safety) to keep it from rolling away.